Bioactive peptides are part of an innate response elicited by most living forms. In plants, they are produced ubiquitously in roots, seeds, flowers, stems, and leaves, highlighting their physiological importance. While most of the bioactive peptides produced in plants possess microbicide properties, there is evidence that they are also involved in cellular signaling. Structurally, there is an overall similarity when comparing them with those derived from animal or insect sources. The biological action of bioactive peptides initiates with the binding to the target membrane followed in most cases by membrane permeabilization and rupture. Here we present an overview of what is currently known about bioactive peptides from plants, focusing on their antimicrobial activity and their role in the plant signaling network and offering perspectives on their potential application.

Appropriate removal of L: -glutamate from the synaptic cleft is important for prevention of the excitotoxic effects of this neurotransmitter. The Na+-dependent glutamate/aspartate transporter GLAST is regulated in the short term, by a transporter-dependent decrease in uptake activity while in the long term, a receptor's-dependent decrease in GLAST protein levels leads to a severe reduction in glutamate uptake. The promoter region of the mouse glast gene harbors an Activator Protein-1 site (AP-1). To gain insight into the molecular mechanisms triggered by Glu-receptors activation involved in GLAST regulation, we took advantage of the neonatal mouse cerebellar prisms model. We characterized the glutamate uptake activity; the glutamate-dependent effect on GLAST protein levels and over the interaction of nuclear proteins with a mouse glast promoter AP-1 probe. A time and dose dependent decrease in transporter activity matching with a decrease in GLAST levels was recorded upon glutamate treatment. Moreover, a significant increase in glast AP-1 DNA binding was found. Pharmacological experiments established that both effects are mediated through alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors, favoring the notion of the critical involvement of glutamate in the regulation of its binding partners: receptors and transporters.

Dextran is an extracellular bacterial polysaccharide for which industrial applications have been found in different areas. Several researchers have optimized the fermentation conditions to maximize dextran production. This study aimed to characterize the dextran of Leuconostoc mesenteroides SF3, which was isolated from the aguamiel of Agave salmiana. To maximize the yield of dextran, the effects of sucrose concentration, temperature, and incubation time were studied. The experiments were conducted using a factorial design and a response surface methodology. L. mesenteroides SF3 produced a maximum yield of dextran (23.8 g/ L ± 4) after 16 h of incubation at 25 °C with 10% sucrose. The functional properties such as water absorption capacity, oil absorption capacity, and emulsion activity of this unique dextran were 361.8% ± 3.1, 212.0% ± 6.7, and 58.3% ± 0.7, respectively. These properties indicate that the dextran produced by L. mesenteroides SF3 is a high-quality polysaccharide with potential applications in the food industry, and the optimized conditions for its production could be used for the commercial production of this dextran, which have significant industrial perspectives.

Different substrates have been implemented for the production of functional beverages. To avoid the presence of pathogens, beverages have been subjected to thermal treatments, such as sterilization or pasteurization, which can interfere with the physicochemical, rheological, functional, and organoleptic properties of the final product. The objective of the present study was to evaluate the effects of heat treatment on the physicochemical properties, such as acidity, pH, total solids, density, total and reducing sugar, as well as the antioxidant activity of a beverage formulated from rice flour (RF) and coconut water (CW). Three beverage formulations were evaluated: A (2% RF; 98% CW), B (5% RF; 95% CW), and C (8% RF; 92% CW), each of which was subjected to two heat treatments: sterilized (121 °C/15 psi/15 min) or pasteurized (60 °C/60 min and subsequently 73 °C/15 s). The heat treatments increased the acidity and reducing sugars but decreased pH, total sugar, and antioxidant activity. As for the rheological properties, the mixtures were pseudoplastic fluid. The physicochemical properties from RF and CW mixtures were dependent on the heat treatment, but these can be introduced as new nondairy substrates for the elaboration of functional beverages to be consumed mainly by those lactose intolerant.